1. Field of the Invention
The present invention relates to an interchangeable lens.
The present invention relates to an interchangeable lens capable of taking a close-up photography with a shooting magnification of a life size and more specifically to a micro lens having an effect of optically deviating an imaging position so as to correct image blur due to vibrations such as a camera shake, etc.
2. Related Background Art
In a photographic camera, a still video camera and the like, there is what we call a macro lens or a micro lens (hereinafter referred to as a micro lens) as a taking lens used for shooting a close-up object. This micro lens is designed to exhibit higher optical performance especially when photographing the close-up object in comparison with a conventional general-purpose taking lens. Needless to say, many of the micro lenses are used not only for photographing the close-up object but also a wide range of the shooting distance extending from infinity to a close distance.
Generally, the taking lens generates large aberration fluctuation as the shooting distance to objects gets closer and a shooting magnification gets higher, and it becomes difficult to correct the aberrations well. To this end, a so-called floating lens has been proposed to repress the aberration fluctuation at the close distance by moving a plurality of lens groups independently when focusing.
However, with this floating lens, the aberration fluctuation is repressed by greatly moving a large and heavy-weighted lens group when focusing, so that the moving of the lens group does not quite contribute to a change in the shooting magnification. Thus, this lens has a shortcoming, e.g., it is not possible to implement quick focus with a so-called auto-focus camera in which the focusing is driven by a motor and the like.
Then, with consideration to the auto focusing, another floating lens has been proposed for reducing a moving amount of a first lens group. This floating lens, however, has still a lens-system construction for moving the large and heavy-weighted lens group, so this floating lens has a shortcoming in that the effect is not sufficient.
Moreover, these floating lenses have another shortcoming. E.g., for gaining sufficient depth of field at the close-up photography, a shooting is required in a state where the lens has to be stopped down and in many cases, inevitable use of slow shutter speed results in image blur, thereby degrading image quality.
Under these backgrounds, a different floating lens has been proposed that is configured so as not to move the first lens and furthermore provides a function of correcting image blurs (e.g., please see Japan Patent Application Laid-open No. 2001-272601).
However, in the floating lens described in Japan Patent Application Laid-open No. 2001-272601, when actually manufacturing this lens, a vibration reduction lens group cannot be arranged sufficiently distant from a lens mount, so that the vibration reduction lens group cannot be contained in a lens barrel together with a vibration reduction drive system for driving the vibration reduction lens group. Moreover, a large vibration reduction coefficient (vibration reduction sensitivity expressed by a ratio of a shift amount of the vibration reduction lens group to a deviation amount of an image point) becomes necessary. Accordingly, the floating lens described in Japan Patent Application Laid-open No. 2001-272601 has no possibility to be put into practical use.